<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8" />
        <title>五子棋</title>
        <style type='text/css'>
            canvas {
                display: block;
                margin: 50px auto;
                box-shadow: -2px -2px 2px #efefef, 5px 5px 5px #b9b9b9;
                cursor: pointer;
            }
            .btn-wrap { 
                display: flex; 
                flex-direction: row; 
                justify-content:center;
            }
            .btn-wrap div { 
                margin: 0 10px;
            }
            div>span {
                display: inline-block;
                padding: 10px 20px;
                color: #fff;
                background-color: #EE82EE;
                border-radius: 5px;
                cursor: pointer;
            }
            div.unable span { 
                background: #D6D6D4; 
                color: #adacaa;
            }
            #result-wrap {text-align: center;}
        </style>
    </head>
    <body>
        <h3 id="result-wrap">--五子棋--</h3>
        <canvas id="chess" width="450px" height="450px"></canvas>
        <div class="btn-wrap">
            <div id='restart' class="restart">
                <span>重新开始</span>
            </div>
            <div id='goback' class="goback unable">
                <span>悔棋</span>
            </div>
            <div id='return' class="return unable">
                <span>撤销悔棋</span>
            </div>
        </div>
        <script type="text/javascript" charset="utf-8">
            var over = false;
            var me = true; //我
            var _nowi = 0, _nowj = 0; //记录自己下棋的坐标
            var _compi = 0, _compj = 0; //记录计算机当前下棋的坐标
            var _myWin = [], _compWin = []; //记录我，计算机赢的情况
            var backAble = false, returnAble = false; 
            var resultTxt = document.getElementById('result-wrap');
            var chressBord = [];//棋盘
            for(var i = 0; i < 15; i++){
                chressBord[i] = [];
                for(var j = 0; j < 15; j++){
                    chressBord[i][j] = 0;
                }
            }
            //赢法的统计数组
            var myWin = [];
            var computerWin = [];
            //赢法数组
            var wins = [];
            for(var i = 0; i < 15; i++){
                wins[i] = [];
                for(var j = 0; j < 15; j++){
                    wins[i][j] = [];
                }
            }
            var count = 0; //赢法总数
            //横线赢法
            for(var i = 0; i < 15; i++){
                for(var j = 0; j < 11; j++){
                    for(var k = 0; k < 5; k++){
                        wins[i][j+k][count] = true;
                    }
                    count++;
                }
            }
            //竖线赢法
            for(var i = 0; i < 15; i++){
                for(var j = 0; j < 11; j++){
                    for(var k = 0; k < 5; k++){
                        wins[j+k][i][count] = true;
                    }
                    count++;
                }
            }
            //正斜线赢法
            for(var i = 0; i < 11; i++){
                for(var j = 0; j < 11; j++){
                    for(var k = 0; k < 5; k++){
                        wins[i+k][j+k][count] = true;
                    }
                    count++;
                }
            }
            //反斜线赢法
            for(var i = 0; i < 11; i++){ 
                for(var j = 14; j > 3; j--){
                    for(var k = 0; k < 5; k++){
                        wins[i+k][j-k][count] = true;
                    }
                    count++;
                }
            }
            // debugger;
            for(var i = 0; i < count; i++){
                myWin[i] = 0;
                _myWin[i] = 0;
                computerWin[i] = 0;
                _compWin[i] = 0;
            }
            var chess = document.getElementById("chess");
            var context = chess.getContext('2d');
            context.strokeStyle = '#bfbfbf'; //边框颜色
            var backbtn = document.getElementById("goback");
            var returnbtn = document.getElementById("return");
            window.onload = function(){
                drawChessBoard(); // 画棋盘
            }
            document.getElementById("restart").onclick = function(){
                window.location.reload();
            }
            // 我，下棋
            chess.onclick = function(e){
                if(over){
                    return;
                }
                if(!me){
                    return;
                }
                // 悔棋功能可用
                backbtn.className = backbtn.className.replace( new RegExp( "(\\s|^)unable(\\s|$)" )," " ); 
                var x = e.offsetX;
                var y = e.offsetY;
                var i = Math.floor(x / 30);
                var j = Math.floor(y / 30);
                _nowi = i;
                _nowj = j;
                if(chressBord[i][j] == 0){
                    oneStep(i,j,me);
                    chressBord[i][j] = 1; //我，已占位置        
                                
                    for(var k = 0; k < count; k++){ // 将可能赢的情况都加1
                        if(wins[i][j][k]){
                            // debugger;
                            myWin[k]++;
                            _compWin[k] = computerWin[k];
                            computerWin[k] = 6;//这个位置对方不可能赢了
                            if(myWin[k] == 5){
                                // window.alert('你赢了');
                                resultTxt.innerHTML = '恭喜，你赢了！';
                                over = true;
                            }
                        }
                    }
                    if(!over){
                        me = !me;
                        computerAI();
                    }
                }         
            }
            // 悔棋
            backbtn.onclick = function(e){
                if(!backAble) { return;}
                over = false;
                me = true;
                // resultTxt.innerHTML = 'o(╯□╰)o，悔棋中';
                // 撤销悔棋功能可用
                returnbtn.className = returnbtn.className.replace( new RegExp( "(\\s|^)unable(\\s|$)" )," " ); 
                // 我，悔棋
                chressBord[_nowi][_nowj] = 0; //我，已占位置 还原
                minusStep(_nowi, _nowj); //销毁棋子                                  
                for(var k = 0; k < count; k++){ // 将可能赢的情况都减1
                    if(wins[_nowi][_nowj][k]){
                        myWin[k]--;
                        computerWin[k] = _compWin[k];//这个位置对方可能赢
                    }
                }
                // 计算机相应的悔棋
                chressBord[_compi][_compj] = 0; //计算机，已占位置 还原
                minusStep(_compi, _compj); //销毁棋子                                  
                for(var k = 0; k < count; k++){ // 将可能赢的情况都减1
                    if(wins[_compi][_compj][k]){
                        computerWin[k]--;
                        myWin[k] = _myWin[i];//这个位置对方可能赢
                    }
                }
                resultTxt.innerHTML = '--五子棋--';
                returnAble = true;
                backAble = false;
            }
            // 撤销悔棋
            returnbtn.onclick = function(e){
                if(!returnAble) { return; }
                   // 我，撤销悔棋
                chressBord[_nowi][_nowj] = 1; //我，已占位置 
                oneStep(_nowi,_nowj,me);                              
                for(var k = 0; k < count; k++){ 
                    if(wins[_nowi][_nowj][k]){
                        myWin[k]++;
                        _compWin[k] = computerWin[k];
                        computerWin[k] = 6;//这个位置对方不可能赢
                    }
                    if(myWin[k] == 5){
                        resultTxt.innerHTML = '恭喜，你赢了！';
                        over = true;
                    }
                }
                // 计算机撤销相应的悔棋
                chressBord[_compi][_compj] = 2; //计算机，已占位置   
                oneStep(_compi,_compj,false);                               
                for(var k = 0; k < count; k++){ // 将可能赢的情况都减1
                    if(wins[_compi][_compj][k]){
                        computerWin[k]++;
                        _myWin[k] = myWin[k];
                        myWin[k] = 6;//这个位置对方不可能赢
                    }
                    if(computerWin[k] == 5){
                        resultTxt.innerHTML = 'o(╯□╰)o，计算机赢了，继续加油哦！';
                        over = true;
                    }
                }
                returnbtn.className += ' '+ 'unable';
                returnAble = false;
                backAble = true;
            }
            // 计算机下棋
            var computerAI = function (){
                var myScore = [];
                var computerScore = [];
                var max = 0;
                var u = 0, v = 0;
                for(var i = 0; i < 15; i++){
                    myScore[i] = [];
                    computerScore[i] = [];
                    for(var j = 0; j < 15; j++){
                        myScore[i][j] = 0;
                        computerScore[i][j] = 0;
                    }
                }
                for(var i = 0; i < 15; i++){
                    for(var j = 0; j < 15; j++){
                        if(chressBord[i][j] == 0){
                            for(var k = 0; k < count; k++){
                                if(wins[i][j][k]){
                                    if(myWin[k] == 1){
                                        myScore[i][j] += 200;
                                    }else if(myWin[k] == 2){
                                        myScore[i][j] += 400;
                                    }else if(myWin[k] == 3){
                                        myScore[i][j] += 2000;
                                    }else if(myWin[k] == 4){
                                        myScore[i][j] += 10000;
                                    }
                                    
                                    if(computerWin[k] == 1){
                                        computerScore[i][j] += 220;
                                    }else if(computerWin[k] == 2){
                                        computerScore[i][j] += 420;
                                    }else if(computerWin[k] == 3){
                                        computerScore[i][j] += 2100;
                                    }else if(computerWin[k] == 4){
                                        computerScore[i][j] += 20000;
                                    }                        
                                }
                            }
                            
                            if(myScore[i][j] > max){
                                max  = myScore[i][j];
                                u = i;
                                v = j;
                            }else if(myScore[i][j] == max){
                                if(computerScore[i][j] > computerScore[u][v]){
                                    u = i;
                                    v = j;    
                                }
                            }
                            
                            if(computerScore[i][j] > max){
                                max  = computerScore[i][j];
                                u = i;
                                v = j;
                            }else if(computerScore[i][j] == max){
                                if(myScore[i][j] > myScore[u][v]){
                                    u = i;
                                    v = j;    
                                }
                            }
                            
                        }
                    }
                }
                _compi = u;
                _compj = v;
                oneStep(u,v,false);
                chressBord[u][v] = 2;  //计算机占据位置
                for(var k = 0; k < count; k++){
                    if(wins[u][v][k]){
                        computerWin[k]++;
                        _myWin[k] = myWin[k];
                        myWin[k] = 6;//这个位置对方不可能赢了
                        if(computerWin[k] == 5){
                            resultTxt.innerHTML = 'o(╯□╰)o，计算机赢了，继续加油哦！';
                            over = true;
                        }
                    }
                }
                if(!over){
                    me = !me;
                }
                backAble = true;
                returnAble = false;
                var hasClass = new RegExp('unable').test(' ' + returnbtn.className + ' ');
                if(!hasClass) {
                    returnbtn.className += ' ' + 'unable';
                }
            }
            //绘画棋盘
            var drawChessBoard = function() {
                for(var i = 0; i < 15; i++){
                    context.moveTo(15 + i * 30 , 15);
                    context.lineTo(15 + i * 30 , 435);
                    context.stroke();
                    context.moveTo(15 , 15 + i * 30);
                    context.lineTo(435 , 15 + i * 30);
                    context.stroke();
                }
            }
            //画棋子
            var oneStep = function(i,j,me) {
                context.beginPath();
                context.arc(15 + i * 30, 15 + j * 30, 13, 0, 2 * Math.PI);// 画圆
                context.closePath();
                //渐变
                var gradient = context.createRadialGradient(15 + i * 30 + 2, 15 + j * 30 - 2, 13, 15 + i * 30 + 2, 15 + j * 30 - 2, 0);
                if(me){
                    gradient.addColorStop(0,'#0a0a0a');
                    gradient.addColorStop(1,'#636766');
                }else{
                    gradient.addColorStop(0,'#d1d1d1');
                    gradient.addColorStop(1,'#f9f9f9');
                }
                context.fillStyle = gradient;
                context.fill();
            }
            //销毁棋子
            var minusStep = function(i,j) {
                //擦除该圆
                context.clearRect((i) * 30, (j) * 30, 30, 30);
                // 重画该圆周围的格子
                context.beginPath();
                context.moveTo(15+i*30 , j*30);
                context.lineTo(15+i*30 , j*30 + 30);
                context.moveTo(i*30, j*30+15);
                context.lineTo((i+1)*30 , j*30+15);
    
                context.stroke();
            }
        </script>
    </body>
</html>